Heat sink



FIG. 1 is a right front top perspective view of our heat sink, in accordance with the present invention;

FIG. 2 is a bottom elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a rear plan view thereof; and,

FIG. 5 is a top plan view thereof. 

The ornamental design for a heat sink, as shown and described. 